tlng ya nomer 5 di jawab???

f(x) = ax + b
f(4) = 4a + b = 19
f(2) = 2a + b = 7

*eliminasi
2a= 19-7
2a= 12
a= 6

2(6) + b = 7
12 + b = 7
b= 7-12 = -5

Bentuk fungsinya : 6x-5